In the construction of fluid systems serving a plurality of work elements through at least first and second circuits, it is desirable to be able to controllably, selectively combine the flows into the circuits. Fluid circuits have heretofore been supplied with control assemblies sufficient to permit fluid combining, however, there arose the problems of the control equipment having to be of undesirably large size in order to accommodate the increased fluid flow through the apparatus. This led to other problems such as compactness, excessive weight, undesirably low sensitivity, and others.
The present invention is directed to overcoming one or more of the problems as set forth above.
According to the present invention, a fluid system has at least first and second circuits each connected to a pressure fluid source. Each of the circuits has at least one preselected work element connected to the fluid source through a respective preselected controlling valve. A first blocker valve is connected on one side to a fluid reservoir and on the other side to the first circuit at a location downstream of the work elements of the first circuit. The first blocker valve is movable between a first position at which the first circuit is in fluid communication with the reservoir and a second position at which communication of the first circuit is blocked from said reservoir. A first control assembly is provided for moving the first blocker valve to the second position in response to actuating the second preselected controlling valve. A second control assembly is provided for passing fluid from the first circuit, at a location downstream of the first circuit work element, to a location in the second circuit downstream of the second preselected controlling valve of the second preselected work element of said second circuit.